In the forthcoming year we intend to concentrate on an examination of the synaptic mechanisms which control somatic activity during the states of wakefulness, quiet sleep and active sleep. In addition the modulation of these basic mechanisms by the reticular formation will also be studied at the cellular level. We will study changes in membrane conductance, including the effect of injected chloride ions and current induced variations in membrane potential. Our secondary objective is to explore the spontaneous changes in trigeminal mesencephalic fiber excitability during wakefulness, quiet sleep and active sleep, and the preterminal excitability of trigeminal mesencephalic fibers following reticular conditioning stimuli during these states.